1. Field of the Invention
The present invention relates to a machine for producing a corrugated cardboard sheet and a process for calibrating the glue gap of such a machine.
2. Background Art
From well-known prior use it is known that, to adjust the width of the glue gap between a corrugating roll and a glue roll in a corrugated cardboard machine, an operator manually holds a so-called splicing tape with a predetermined thickness between the corrugating roll, which has a corrugated sheet placed on it, and the glue roll. The distance between the glue roll and the corrugating roll is then reduced. This is done while the corrugating roll is rotating and the glue roll is rotating. The width of the glue gap is reduced until the splicing tape is pulled in by the rotating rolls. The glue gap has then been adjusted to the thickness of the splicing tape. However, this method of adjusting the glue gap has the disadvantage that the adjustment is time-consuming and cannot be done automatically. There furthermore is the danger that the hand in which the operator is holding the splicing tape may be pulled into the glue gap and may be injured.
A machine for producing a corrugated cardboard sheet is known from DE 197 15 174 A1. The glue roll is pushed directly against the corrugated sheet that is wound around a portion of the corrugating roll. There is no glue gap between the corrugated sheet and the outer face of the glue roll. To adjust a predetermined contact pressure between the glue roll and the corrugated sheet, a force-measuring unit is provided, as well as a means for changing the distance between the corrugating roll and the glue roll. The shortcoming of this arrangement is that the glue roll pushes against the corrugating roll with a predetermined force, which may result in damage to the glue roll.
The present invention, therefore, has as its object to provide a machine for producing corrugated cardboard in which the adjustment of the glue gap can be carried out in the simplest possible manner and automatically.
This object is met with a machine for producing a corrugated cardboard sheet, which incorporates at least one corrugated sheet with corrugation crests and at least one liner sheet that is glued to the corrugation crests, comprising
at least one corrugating roll, which serves to give the corrugated sheet its shape, incorporating
a corrugating-roll axis around which the corrugating roll can rotate,
a first corrugating-roll end with a first corrugating-roll bearing journal,
which is mounted in a first corrugating-roll bearing, and
a second corrugating-roll end with a second corrugating-roll bearing journal, which is mounted in a second corrugating-roll bearing,
a gluing device for applying glue onto the corrugation crests by means of a glue roll
incorporating a glue-roll axis, around which the glue roll can rotate, and
which extends parallel to the corrugating-roll axis,
incorporating a first glue-roll end with a first glue-roll bearing journal mounted in a first glue-roll bearing, which is assigned to the first corrugating-roll bearing,
incorporating a second glue-roll end with a second glue-roll bearing journal mounted in a second glue-roll bearing, which is assigned to the second corrugated-roll bearing,
delimiting, between itself and the corrugating roll, a glue gap of a width B, and
advanceable towards the corrugating roll for adjusting the width B of the glue gap, and
a calibration device for adjusting the width B of the glue gap having at least one contact-pressure unit for pressing a glue-roll bearing against the corresponding corrugating-roll bearing with a contact-pressure force A,
at least one force-measuring unit for measuring a force of the bearing contact pressure P between the pressed-on glue-roll bearing and the corresponding corrugating-roll bearing,
at least one adjusting unit for adjusting a bearing distance L between a pressed-on glue-roll bearing and the corresponding corrugating-roll bearing, and
at least one control unit, which is connected to the at least one force-measuring unit and the at least one adjusting unit for the transfer of signals, and which activates the at least one adjusting unit in such a way that at least one bearing distance L is reduced, until the force of the bearing contact pressure P decreases based on the glue roll and the corrugating roll coming into contact with one another.
According to another aspect of the invention, a process for calibrating a machine for producing a corrugated cardboard sheet comprises the following steps,
providing a machine for producing a corrugated cardboard sheet, which incorporates at least one corrugated sheet with corrugation crests and at least one liner sheet that is glued to the corrugation crests, comprising
at least one corrugating roll, which serves to give the corrugated sheet its shape, incorporating a corrugating-roll axis around which the corrugation roll can rotate, a first corrugating-roll end with a first corrugating-roll bearing journal, which is mounted in a first corrugating-roll bearing, and a second corrugating-roll end with a second corrugating-roll bearing journal, which is mounted in a second corrugating-roll bearing,
a gluing device for applying glue onto the corrugation crests by means of a glue roll, incorporating a glue-roll axis, around which the glue roll can rotate and which extends parallel to the corrugating-roll axis, incorporating a first glue-roll end with a first glue-roll bearing journal mounted in a first glue-roll bearing, which is assigned to the first corrugating-roll bearing, incorporating a second glue-roll end with a second glue-roll bearing journal mounted in a second glue-roll bearing, which is assigned to the second corrugated-roll bearing, delimiting, between itself and the corrugating roll, a glue gap of a width B, and advanceable towards the corrugating roll for adjusting the width B of the glue gap, and
a calibration device for adjusting the width B of the glue gap having at least one contact-pressure unit for pressing a glue-roll bearing against the corresponding corrugating-roll bearing with a contact-pressure force A, at least one force-measuring unit for measuring a force of the bearing contact pressure P between the pressed-on glue-roll bearing and the corresponding corrugating-roll bearing, and at least one adjusting unit for adjusting a bearing distance L between a pressed-on glue-roll bearing and the corresponding corrugating-roll bearing,
positioning of the glue roll in a starting position in which the glue roll is not in contact with the corrugating roll, and
reduction of at least one bearing distance L by means of the adjusting unit, until the force of the bearing contact pressure P decreases due to a contact between the glue roll and the corrugating roll.
The gist of the invention entails pushing the bearing of the glue roll against the bearing of the corrugating roll with a predetermined force, and measuring the force of the bearing contact pressure between the two bearings. The distance between both bearings is subsequently reduced until the glue roll comes into contact with the corrugating roll. This is detected because the force of the bearing contact pressure decreases, since a portion of the contact-pressure force is transferred via the rolls.